The WatchPAT 200 (TM) is a wrist worn diagnostic device for detecting SDB. Its main part is the measurement of the peripheral arterial tone (PAT) via a plethysmographic based finger-mounted probe. It can measure the level of sympathetic activation of the autonomic nervous system. Pulse rate, oxygen saturation and snoring/body position levels are calculated, too. A software program (zzzPAT (TM)) with a special algorithm analyzes the raw data and creates a sleep report. Therefore the property of the WatchPAT 200 (TM) proclaims that the WatchPAT 200 (TM) can detect sleep events and SDB.